The present invention relates to a method of removing local defective portions in a veneer sheet such as knotholes, dead knots, rotten spots and the like and filling the routed-out openings with defect-free patching pieces.
Various methods of the type described are known in the art as stated for instance in "PLYWOOD PRODUCTION", 2nd Edition, pp 127-131 written by Haruo Watanabe and published by Morikita Shuppan.
One of the known methods consists in cutting out a defective portion from a veneer sheet at a suitable first station and manually seating in the resulting opening of the veneer sheet a pre-shaped patch common in shape and size to the opening at a second station remote from the first station.
Another known method which is generally referred to as Reiman's method employs a sequence of mechanical actions for performing the removing operation and plugging operation of the first known method at the same station. This method compared with the first method saves a substantial amount of labor and facilitates an automatic patching process.
Such conventional methods involve a common drawback originating from the use of essentially independent punches (cutting members) for removing a defective portion and forming a patch or plug to be seated in the resultant opening. The two different punches need an identically high precision which in turn calls for such a skill for their precision control, centering at mounting positions etc. This makes it difficult to favorably keep the patch or plug seated in the hole of a veneer sheet in register therewith. Meanwhile, a patch or a plug has heretofore been inserted manually in a veneer sheet as mentioned after the removal of the defect of the veneer sheet or such a manual procedure has been simply replaced by a mechanical procedure. This gives rise to another drawback concerning the efficiency of operations. Another factor which limits the efficiency or workability is that patching is carried out only at a fixed location and a defective portion of a veneer sheet must be moved by manual work all the way to a position just below a punch. Thus, the efficiency obtainable with the conventional method is not more than the one of a patching technique with a fixed patching position.